In 2004, Diener left the Green Party, founding the Green Liberals together with National Councillor and former president of the Zurich Green Party, Martin Bäumle.
In the second round of the 2007 Council of States elections in Zurich, Diener won the majority before Swiss People's Party chairman Ueli Maurer. Diener's seat is one of five (out of 46) not held by members of the parties represented in the Swiss Federal Council (besides fellow Green Liberal, Markus Stadler of Uri, Werner Luginbühl of Canton of Bern and the two of the Green Party, Robert Cramer of Geneva and Luc Recordon of Vaud).
- Biography of Verena Diener on the website of the Swiss Parliament. (German)